Particles such as pharmaceutical particles have been produced by dispersing physiologically active substances such as pharmaceutical compounds with dispersing agents.
Examples of methods for producing the particles such as the pharmaceutical particles include pulverization methods and emulsification methods.
In the pulverization methods, the particles are obtained by pulverizing the physiologically active substances such as the pharmaceutical compounds using a variety of mills, optionally with the addition of the dispersing agents or a variety of pulverizing media (e.g., zirconium silicate and glass) typically in the form of spherical beads. In addition, various methods including a variety of pulverization techniques such as airjet pulverization and wet pulverization have been used.
The pulverization methods are advantageous in that the particles such as the pharmaceutical particles are capable of being obtained easily and conveniently. However, the pulverization methods have the problems described below. Firstly, it is difficult to allow the particles such as the pharmaceutical particles to have a smaller particle diameter. Secondly, the resultant particles such as the pharmaceutical particles have a wider particle size distribution. Thirdly, bioavailability is not improved when the pharmaceutical particles are orally administered.
In the emulsification methods, oil phases including the physiologically active substances such as the pharmaceutical compounds, the dispersing agents, and surfactants are added to and dispersed into aqueous phases. Then, the thus-produced dispersion liquid is dried to obtain the particles such as the pharmaceutical particles. The emulsification methods are advantageous in that the particles having a small particle diameter are capable of being produced relatively easily and conveniently. However, the emulsification methods have the problem that only pharmaceutically available surfactants are capable of being used as the surfactants. Moreover, when the oil phases include water-soluble materials, the water-soluble materials migrate from the oil phases to the aqueous phases. As a result, the resultant particles such as pharmaceutical particles are not capable of being controlled in particle diameter, resulting in a wider particle size distribution. Therefore, bioavailability is not improved when the pharmaceutical particles are orally administered.
Therefore, there have been proposed, as methods for solving the aforementioned problems, methods for producing pharmaceuticals in which pharmaceutical particles are produced using spray-drying methods (see, for example, PTLs 1 and 2).